The new right of natural fathers to contest - reform on 1 April 2026

Dr Marko Oldenburger, Hamburg

With effect from 1 April 2026, the „Act Implementing the Ruling of the Federal Constitutional Court on the Avoidance of Paternity“ came into force. This is the legislator's response to the constitutional requirements and fundamentally reorganises the law of avoidance. The following article provides a precise overview of the main changes and their practical effects.

1. § 1600 BGB new version: Introduction of a 4-stage examination

The centrepiece of the reform is the complete restructuring of § 1600 BGB. The contestation procedure now follows a four-stage examination:

First stage:
In the case of underage children, the challenge is generally successful if none social-familial relationship exists between the child and the legal father. A legal presumption assumes the absence of such a relationship within the first year after paternity is established.

Second stage:
Within the one-year period, the legal father can prove that a social family relationship has already been established in order to rebut the presumption.

Third stage:
If it exists (either after the expiry of the one-year period or on the basis of a special presentation), the biological putative father can counter this with his own efforts or an existing social family relationship. Failed efforts by the biological father may also be taken into account, provided he is not responsible for their failure.

Fourth stage:
If there are two competing paternity positions, the court must decide in favour of (and against) one father. Only if the continuation of paternity is in the best interests of the child, taking into account the legitimate interests of the parties involved, can the court decide in favour of (or against) one father. required the challenge would be unfounded. To this end, the family court will have to comprehensively assess existing ties and the consequences of a paternity swap; the duration and intensity of the ties and, for the first time, domestic violence must also be taken into account.

2. Contestation period remains in place

The contestation period is still two years. What is new, however, is that an existing socio-familial relationship can expressly does not inhibit. A missed deadline can therefore no longer be compensated by a later resumption (à 4).

3. Personal contestation and the role of the child

Contestation will in future be strictly to explain personally. Different rules apply to minors depending on their age. Particularly relevant in practice:

• A Child of legal age can prevent the contestation, by contradicting it.
• A child with limited legal capacity (over the age of 14) must declare the cancellation themselves and does not require the consent of their legal representative(s).

4. Retrial proceedings (Section 185a FamFG new version)

Reopening of completed proceedings has been possible since 1 April 2026, including for old cases:

• The prerequisite is the Elimination of the previously existing social-familial relationship
• The following apply Age-dependent waiting periods (2-4 years)
• Multiple retakes are possible

This opens up new opportunities in old cases, but at the same time harbours considerable procedural risks and burdens for the courts.

5. Blocking effect for ongoing proceedings

A pending The procedure for establishing genetic paternity means that paternity acknowledgement can be Pending ineffective is. An exception applies to the actual genetic father, who can recognise his paternity on record in the pending proceedings by submitting a parentage report.

6. New regulation of consent requirements

Recognition of paternity still requires consent. What is new, however, is the child's duty of consent, which is independent of parental custody. It has been made age-dependent. This significantly strengthens the position of the child, as a lack of personal consent (from children older than 14) can prevent recognition.

7. Introduction of a „quadruple declaration“ (§ 1595a BGB new version)

A significant innovation is the possibility of a amicable paternity swap without court proceedings. Required are:

• Consent of mother, legal father, biological father and child
• Proof of genetic ancestry.

The result is the retroactive establishment of paternity from birth. This regulation creates a practical alternative to litigation. Neither divorce nor contestation are necessary if there is agreement plus proof of genetic parentage.

8. Evaluation and outlook

In principle, the reform convincingly implements the requirements of the Constitutional Court. Particularly noteworthy are

• the structured 4-step test
• the introduction of consensual solutions

However, this should be viewed critically:

• up to 5 retrials for young children
• the high investigation and assessment costs for the family courts
• Longer procedures due to lack of priority.

Overall, the new regulation leads to a significant Increasing complexity in parentage law and will have a lasting impact on family court practice.

Conclusion:
The new right of avoidance strengthens the position of biological fathers, but at the same time places high demands on all parties involved. For legal practice, this means in particular early strategic advice and careful examination of deadlines and procedural options. If you have failed in your attempt to become a parent due to a blocking social family relationship, you will in any case have a second chance from 1 April 2026.